Method for forming slip rings



y 3, 1960 P. w. NIPPERT 2,934,813

METHOD FOR FORMING SLIP RINGS Filed July 9, 1953 2 Sheets-Sheet l I I H II i F L: I Ti i i l y I \Q 1 I w F 2 E 47 I. A I M INVENTOR.

Pfll/L m NIPPERT MKfI/W,

A TTOPNEY y 3, 1960 P. w. NIPPERT 2,934,813

METHOD FOR FORMING sup RINGS Filed July 9, 1953 2 Sheets-Sheet 2 lllllllll mum 8 llllllll l i HIHHBJLD 8 l L42 Fl .9 Fl ll INVENTOR.

/u/z. m A/IPPERT ATTORNEY METHOD FOR FORMBVG SLIP RINGS Paul W. Nippert, Columbus, Ohio, assignor to The Nippert Electric Products Company, Columbus, Ohio, a V corporation of Ohio Application July 9, 1953, Serial No. 366,887

9 Claims. (Cl. 29-1555) The present invention relates to improvements in slip ring conductors for rotating electrical devices, and to a method of forming such conductors from sheet metal stock. Such conductors are generally known as slip rings.

An object of the present invention is to provide a. method of forming slip rings whereby sheet metal stock is first pressed into the form of a cup-shaped element, with such element being later coined and punched to provide a finished slip ring.

Another object of the present invention is to provide a method of forming slip rings whereby sheet metal stock is first pressed into the form of a cup-shaped element having a radius at the junction of the wall and bottom of such element and whereby such element is later coined in a manner such that the available pressure is concentrated on certain portions of the elementto form a 90 junction for the wall and bottom of the cup-shaped element.

Another object of the present invention is to provide a method of forming slip rings whereby sheet metal stock is first pressed into the form of a cup-shaped element having a wall portion and a bottom portion, and whereby a hole is punched in such bottom portion to form the cup-shaped element as a ring.

Another object of the present invention is to provide an improved slip ring having novel means for securing a wire to such slip ring.

Another object of the present invention is to provide a method of forming slip rings whereby sheet metal stock is pressed, coined, and punched into the form of a ringshaped element having a plane bottom surface, and whereby a depression is formed in said bottom surface near the main hole therein. Such depression serves to prevent bulged metal from extending beyond the plane bottom surface when a wire is later secured to the slip ring by crimping.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein preferred forms of embodiments of the invention are clearly shown.

In the drawings:

- Fig. 1 is a side elevational view taken partially in section on a vertical plane through the center of a blanking and forming die, and showing the first operation of the present invention;

Fig. 2 is a top elevational view of the lower of the blanking and forming die of Fig. 1;

Fig. 3 is a side elevational view, taken partially in section .on a vertical plane through the center of a coining die, and showing the second operation of the present invention;

' Fig. 4 is a fragmentary side sectional view corresponding to the view of Fig. 3 and enlarged relative thereto;

' Fig. 5 is a side elevational view, taken partially in section on a vertical plane through'the center of a punch die, showing the third operation of thepresent invention;

portion 2,934,8l3 Fatented May 3, 1960 Fig. 6 is a perspective view of a circular work piece blanked from sheet metal in accordance with the present invention;

Fig. 7 is a perspective view, partially in broken section, showing the work piece in a cup-shaped form after it has been subjected to a forming operation;

Fig. 8 is a perspective view showing the work piece after it has been subjected to a coining operation;

Fig. 9 is a side sectional view corresponding to Fig. 8, with the sectional view being taken on the line 9--9 of Fig. 8;

Fig. 10 is a perspective view showing the work piece in a ring-shaped form after it has been subject to a punching operation;

Fig. 11 is a side sectional view corresponding to Fig. 10, with the sectional view being taken on the line 11-11 of Fig. 10;

Fig. 12 is a fragmentary sectional view corresponding to Fig. 11 and taken along the line 12-12 of Fig. 11;

Fig. 13 is a fragmentary sectional view similar to that of Fig. 12; and

Fig. 14 is a side elevational view, partially in section, showing two slip rings of the present invention in assembled relationship.

Referring to the drawing and more particularly to Fig. l, a die set is indicated generally at 10. The die set comprises an upper portion 11 to which a male portion 12 of a blanking and forming die is secured. A female portion 13 of a blanking and forming die is secured to a lower portion 14 of the die set. .The female portion adapted to receive long strips of sheet metal stock. The

male portion of the die is provided with a shearing edge 20 which is positioned in operative relationship with a second shearing edge 21 on the female die portion. The

male die portion is adapted to be moved downwardly into operative relationship with the female die portion so that a circular work piece 25, Fig. 6, can be blanked from a sheet of metal which has been inserted into the slot 15.

After the circular work piece 25 is blanked from the sheet of stock, and upon further downward movement of the male die portion 12, a central portion of the work piece will be forced downwardly against the plug 26, and upon still further downward movement of the upper die portion 12, the work piece will be formed around a protrusion 26 which is provided on the female die portion. At the same time, a cavity portion 27 in the male die portion 12 will be forced downwardly around such work piece. In this manner a circular piece of sheet metal,

shown in Fig. 6, is formed to the shape of a cup as seen at 25 in Fig. 7. Upon withdrawal of the upper die portion 12, the cup-shaped work piece 25 is disengaged from the cavity 27 by the ejector 30. At the completion of the blanking and forming operation, it should be noted that the work piece 25 will have a substantial radius at a corner 32, with such corner being at the junction of a side wall portion 33 and a bottom portion 34.

For the next operation, the cup-shaped work piece 25 is placed in a press indicated generally at 40, Fig. 3. A coining die, indicated generally at 41, is secured to the press 40 with such die having an upper portion 42.

positioned in operative relationship with a lower portion 43. The upper portion 42, of the coining die, is proof the coining die which come in direct contact withthe' work piece for applying pressure thereto. In this view such portions are shown enlarged relative to the view of is to eliminate the radius at the corner 32 on the work piece, as seen in Fig. 7, and to form a substantially 90 corner on such work piece at 32, as seen in Fig. 8. This radius is eliminated by flowing metal in the wall 25 of the work piece toward the corner 32, and such flowing being caused by the application of'pressure to the work piece by the coining die. To efliciently accomplish such flow of metal, it is advantageous to concentrate the available press pressure at the outer periphery of the work piece, and, in addition, it is desirable to confine the flow of metal so that such flow will be caused to occur at the proper portion of the work piece, namely, in the outer wall 25 and in a direction toward the corner 32.

In order to concentrate the available press pressure at the outer periphery of the work piece,a recess '51 is formed in the surface 47 of the plug 46. A second recess 52 is formed in the surface 53 of the lower die portion 43. Because of these recesses, the peripheral portion of the upper die surface 47 and the peripheral portion of the lower die surface 53, will be caused to engage opposite sides of the peripheral portion of the bottom 35 of the work piece. Such initial engagement of the work piece by the coining die occurs upon the initial movement of the upper die portion toward the lower die portion. A second pressure surface 55 is formed on the lower die portion 43 at the base of the protrusion 48 so that such surface 55 can contact the edge 56 of the wall of the work piece in order to transmit pressure in a direction longitudinal to the wall of the work piece for flowing metal in such wall 33 towards the corners 32.

To further confine the available pressure to the periphery of the work piece and to concentrate the flow of metal at such periphery, a ring-shaped protrusion 57 is formed on the upper die surface 47 at the periphery of the recess 51. When the upper die portion is moved apparent.

surface of the work piece and, in this manner, the ring- Y shaped protrusion serves as a pressure or flow lock to direct the effectiveness of the press action to the periphery of the work piece the direction of the flow of the metal is indicated by the arrows 60, as seen in Fig. 4. To eject the work piece from the coining die, the upper die portion is moved away from engagement with the lower die portion and the upper plug 46 is caused to move downwardly by action of the ejector rod 62, and the work piece is thereby ejected from the recess 45. After the work piece has been coined in the manner just described, a ring-shaped depression 63, Fig. 9, will be present in the outer surface of the bottom of such work piece, with such depression being due to the indenture of such surface by the ring-shaped protrusion 57 during the coining operation.

To form the work piece to the shape of a ring as seen in Fig. 10, such work piece is next subjected to the operation of a punch press which is indicated generally at 70 in Fig. 5. A punch 71 is mounted in the press in operative relationship with a die 72. The die 72 is provided with a shoulder portion 73 for receiving and indexing the work piece. To form the hole 75 in the work piece, as is seen in Fig. 10, the punch is rammed.

downwardly against the bottom of the work piece and a slug 76 is blasted ahead of the punch 71, as seen in Fig. 5. At the same time the hole 75 is being punched, a depression 78, Fig. 10, is formed in the bottom surface of the work piece, and at the same time the depression 78 is formed, a corresponding protrusion 85, as best seen in Fig. 11, will be formed on the inner bottom surface of the work piece at the edge of the hole 75. Such protrusion 85 necessarily results from the method of forming the depression 78. To form such depression in the work piece, a corresponding depression 87 is provided in the upper surface 88 of the die 72. Hence, when the punch 71 is rammed downwardly, metal from 4 the bottom of the work piece is flowed downwardly into the depression 87 in the die to form the protrusion 85. At the same time the protrusion is formed the corre' sponding depression 78 will result in the outer surface of the bottom of the work piece.

After the forming of the slip ring is completed, it is necessary to secure a conducting wire 80, Fig. 12, to such slip ring. To provide for this, an axially extending hole 79 is formed through the bottom surface of the work piece at the depression 78, as seen in Figs. 10 through 13. The uninsulated end of such Wire is then inserted into the hole 79 and a radially extending crimping indenture 81 is formed into the wall of the hole 75 so that the end of the wire is crimped into the slip ring as seen in Fig. 13. Itisduring the forming of such crimp that the importance of the depression 78 becomes When the crimping indenture is being formed, metal in the bottom of the work piece, in the vicinity of depression 78, will be bulged outwardly in an axial direction to partially'fill in the depression 78. Since the depression 78 is present, the bulging of metal can-be permissibly tolerated without causing a protrusion beyondthe outer bottom surface of the work piece. In other words, the depression 78 is provided before the crimping operation so that metal, bulged outwardly by such crimping operation, will not cause a disturbing protrusion on the bottom surface of the finished slip ring. Prevention of such protrusion is necessary so that the slip rings can be assembled in close relationship on a core 82 in the manner shown in Fig. 14.

To eject the punch work piece from the press 70, the punch portion 71 is moved upwardly, and when the work piece engages the member of the press, such work piece will be stripped from engagement with the punch 71.

The work piece is next subjected to the drilling operation, previously described, to produce the hole shown at 79 in Fig. 11. The conductor wire 80 is then in serted into the hole 79 and the crimping operation is performed in the manner previously described. The slip ring, with the wire attached is then ready to be assembled co-axially and in abutting relationship with other similarly formed slip rings. As is seen in Fig. 14, a sleeve 83 of suitable insulating material is provded between the core 82 and the slip rings mounted thereon; A disk 84 of similar insulating material is also provided between abutting surfaces of adjacent slip rings.

While the forms of embodiments of the present invention as herein disclosed constitute preferred forms, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow:

I claim:

1. The steps in the method of forming slip ring conductors for rotary electrical devices which comprises blanking and forming a cup-shaped element from sheet metal, with such element having a wall portion, a bottom portion, and a radius at the junction of such portions; inserting the element in a die comprising a first die portion having on the deforming surface thereof an annular central recess, a peripheral recess, and an annular projection extending between said recesses, a second die portion having on the deforming surface thereof an annular central recess and an annular projection surrounding said recess and cooperating with said first mentioned annular projection to form an annular zone of relatively high pressure application, said die including means forming a cylindrical confining surface for the periphery of said element; applying pressure to the element by moving one of said die portions relative to the other of said die portions whereby the force exerted by said die portions is concentrated on said annular zone to produce a relatively high degree of metal displacement in the peripheral portion of said element and towards said radius; applying additional pressure to the element to form a.substantially ninety degree junction for the wall and bottom portions by flowing metal in the wall portion toward the' bottom portion; and forming a shaft receiving hole centrally through said bottom portion of said element.

:2. The steps in the method of forming slip ring conductors for rotary electrical devices which comprises blanking and forming a cup-shaped element from sheet metal, which such element having a wall portion, a bottom portion, and a radius at the junction of such portions; inserting the element in a die portion comprising a first die portion having on the deforming surface thereof a central pressume applying surface and a peripheral recess surrounding said central pressure applying surface, a second die portion having on the deforming surface thereof an annular central recess and an annular projection surrounding said recess and cooperating with said central pressure applying surface to form an annular zone of relatively high pressure application, said die including means forming a cylindrical confining surface for the periphery of said element; applying pressure to the element by moving one of said die portions relative to the other of said die portions whereby the force exerted by said die portions is concentrated on said annular zone to produce a relatively high degree of metal displacement in the peripheral portion of said element and towards said radius; applying additional pressure to the element to form a substantially ninety degree junction for the wall and bottom poltions for flowing metal in the wall portion toward the bottom portion; and forming a shaft receiving hole centrally through said bottom portion of said element.

3. The steps in the method of forming slip ring conductors for rotary electrical devices which comprises blanking and forming a cup-shaped element from sheet metal, with such element having a wall portion, a bottom portion, and a radius at the junction of such portions; inserting the element in a die comprising a first die portion having on the deforming surface thereof an annular central recess, a peripheral recess and an annular projection extending between said recesses, a second die portion having on the deforming surface thereof a pressure applying surface the periphery of which cooperates with said annular projection to form an annular zone of relatively high pressure application, said die including means forming a cylindrical confining surface for the periphery of said elements; said pressure applying surface including a centrally located recess applying pressure to the element by moving one of said die portions relative to the other of said die portions whereby the force exerted by said die portions is concentrated on said annular zone to produce a relatively high degree of metal displacement in the peripheral portion of said element and towards said radius; applying additional pressure to the element to form a substantially ninety degree junction for the wall and bottom portions by flowing metal in the wall portion toward the bottom portion; and forming a shaft receiving the hole centrally through said bottom portion of said element.

4. The steps in the method of forming slip ring conductors for rotary electrical devices which comprises blanking and forming a cup-shaped element from sheet metal, with such element having a wall portion, a bottom portion, and a radius at the junction of such portions; inserting the element in a die comprising a first die portion having on the deforming surface thereof an annular central recess, a peripheral recess and an annular projection extending between said recesses, a second die portion having on the deforming surface thereof an annular central recess and an annular projection surrounding said recess and cooperating with said first mentioned annular projection to form an annular zone of relatively high pressure application, said die including means forming a cylindrical confining surface for the periphery of said element; applying pressure to the element by moving one of said die portions relative to the other of said die portions whereby the force exerted by said die portions is concentrated on said'annular zone to produce a relatively high degree of metal displacement in the peripheral portion of said element and towards said radius; applying additional pressure to the element to form asubstantially ninety degree junction for the wall and bottom portions by flowing metal in the wall portion toward the bottom portion forming a shaft receiving hole centrally through said bottom portion of said element; forming a depres sion in a bottom surface of said element adjacent an edge of said shaft receiving hole; and forming a wire receiving hole in said surface of said bottom portion at said depression.

5. The steps in the method of forming slip ring c'onductors for rotary electrical devices which comprises blanking and forming a cup-shaped element from sheet metal, with such element having a wall portion, a bot tom portion, and a radius at the junction of such portions; inserting the element in a die comprisinga first die portion having on the deforming surface thereof a pressure applying surface and a peripheral recess surrounding said central pressure applying surface, a second die portion having on the deforming surface thereof an annular central recess and an annular projection surrounding said recess and cooperating with said central pressure applying surface to form an annular zone of relatively high pressure application, said die including means forming a cylindrical confining surface for the'periphery of said element; applying pressure to the element by moving one of said die portions relative to the otherof said die portions whereby the force exerted by said die portions is concentrated on said annular zone to produce a relatively high degree of metal displacement in the peripheral portion of said element and towards said radius; applying additional pressure to the element to form a substantially ninety degree junction for the wall and bottom portions by flowing metal in the wall-portion toward the bottom portion; and punching a shaft receiv ductors for rotary electrical devices which comprises blanking and forming a cup-shaped'element from sheet metal, with such element having a wall-portion, a bottom portion, and a radius at the junction of such portions; inserting the element in a die comprising a first die portion having on the deforming surface thereof an annular central recess, a peripheral recess and an annular projection extending between said recesses, a second die portion having on the deforming surface thereof a pressure applying surface the periphery of which cooperates with said annular projection to form an annular pattern of relatively high pressure application, said die including means forming a cylindrical confining surface for the p.- riphery of said element; applying pressure to the element by moving one of said die portions relative to the other of said die portions whereby the force exerted by said die portions is concentrated in said annular pattern on said peripheral portion of said element to produce a relatively high degree of metal displacement in the peripheral portion of said element and towards said radius; applying additional pressure to the element to form a substantia ly ninety degree junction for the wall and bottom portions by flowing metal in the wall portion toward the bottom portion; forming a shaft receiving hole centrally through said bottom portion of said element; forming a depression in a bottom surface of said element adjacent an edge of said shaft receiving hole; and forming a wire receiving hole in said surface of said bottom portion at said depression.

7. The steps in the method of forming slip ring conductors for rotary electrical devices which comprises blanking and forming a cup-shaped element from sheet metal, with such element having a wall portion, a bottom portion, and a radius at the junction of such portions; inserting the element in a die comprising a first die portion having on the deforming surface thereof an annular central recess, a peripheral recess and an annular projection extending between said recesses, a second die portion having on the deforming surface thereof an annular central recess and an annular projection surrounding said recess and cooperating with said first mentioned annular projection to form an annular pattern of relatively high pressure application, and a block having an annular aperture, the walls of said aperture surrounding and closely fitting the outer peripheries of said die; applying pressure to the element by moving one of said die portions relative to the other of said die portions whereby the force exerted by said die portions is concentrated in said annular pattern on said peripheral portion of said element to produce a relatively high degree of metal displacement in said peripheral portion and towards said radius; applying additional pressure to the element to form a substantially ninety degree junction for the wall and bottom portions by flowing metal in the wall portion toward the bottom portion; and forming a shaft receiving hole centrally through said bottom portion.

8. The steps in the method of forming slip ring conductors for rotary electrical devices which comprises blanking and forming a cup shaped element from sheet metal, with such element having a wall portion, a bottom portion, and a radius at the junction of such portions; inserting the element in a die comprising a first .die portion having on the deforming surface thereof a pressure applying surface and a peripheral recess surrounding said central pressure applying surface, a second die portion having on the deforming surface thereof an annular central recess and an annular projection surrounding .said recess and cooperating with said central pressure applying surface to form an annular pattern of relatively high pressure application, and a block having an annular aperture, the walls of said aperture surrounding and closely fitting the outer peripheries of said die; applying pressure to the element by moving one of said die portions relative to the other of said die portions whereby the force exerted !by said die portions is concentrated in said annular pattern on said peripheral portion of said element to produce a relatively high degree of metal displacement in said peripheral portion and towards said radius; applying additional pressure to the element to form a substantially ninety degree junction for the wall and bottom portions for flowing metal in the wall portion toward the bottom portion; and forming a shaft receiving hole centrally through said bottom portion.

9. The steps in the method of forming slip ring conductors for rotary electrical devices which comprises blanking and forming a cup-shaped element from sheet metal, with such element having a wall portion, a bottom portion, and a radius at the junction of such portions; inserting the element in a die comprising a first die portion having on the deforming surface thereof an annular central recess, a peripheral recess "and an annular projection extending between said recesses, a second die portion having on the deforming surface thereof an an nular central recess and a projection surrounding said recess in an annular pattern and disposed inwardly of said projection on said first die portion, said die including means forming a cylindrical confining surface for the periphery of said element; applying pressure to the element by moving one of said die portions relative to the other of said die portions 'whereby the force exerted by said die portions is concentrated in said annular pattern on said peripheral portion of said element to pro duce a relatively high degree of metal displacement in said peripheral portion and towards said radius; applying additional pressure to the element to form a substantially ninety degree junction for the wall and bottom portions by flowing metal in the wall portion toward the bottom portion; and forming a shaft receiving hole centrally through said bottom portion.

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